Viagra (sildenafil) is a brand-name prescription medication. The Food and Drug Administration (FDA) has approved it to treat erectile dysfunction (ED). Doctors usually prescribe it to use as needed before sexual activity.

Here are some fast facts about Viagra:

As with other drugs, Viagra can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Viagra, including details about its uses, see this article.

Viagra can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Viagra in clinical trials:

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Viagra use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Viagra’s prescribing information.

Mild side effects that have been reported with Viagra include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Viagra and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Viagra may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Viagra’s prescribing information.

If you develop serious side effects while taking Viagra, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported include:

* To learn more about these side effects, see the “Side effect specifics” section below.

Viagra may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Can Viagra cause long-term side effects?

Most of Viagra’s side effects are mild and temporary, lasting a few days to weeks. However, Viagra can cause serious side effects* that can affect your health long term.

For example, Viagra can cause non-arteritic anterior ischemic optic neuropathy (NAION),† which can result in permanent vision loss. (NAION is a condition that can cause damage to the optic nerve, the nerve responsible for your vision). Viagra can also cause priapism,† which can have long-term effects on your health if it isn’t quickly treated. (Priapism is a long lasting and painful erection that won’t go away.)

If you have side effects that last longer than expected, bother you, or become severe, be sure to talk with your doctor or pharmacist.

* For information about serious side effects of Viagra, see the “Serious side effects of Viagra” section above.
† To learn more about these side effects, see the “Side effect specifics” section below.

Does Viagra cause certain side effects in older adult males?

No, Viagra is not known to cause specific side effects in older adults (ages 65 years and over). In clinical trials, there weren’t any differences in side effects in older adults compared to younger adults.

However, older adults who take Viagra tend to absorb more of the drug in their body. This can increase the risk of side effects. So, it’s possible that being older may increase your risk of side effects from Viagra.

If you’re concerned about taking Viagra due to your age, talk with your doctor. They can help determine whether it’s safe for you and if you would need a lower starting dose of the drug. (For information about the dosages of Viagra, see this article.)

Is Viagra safe to take?

Yes, Viagra is typically safe to take if your doctor knows your complete medical history and you take it as prescribed. However, serious side effects from the medication are possible. (For details, see the “Serious side effects” section above.)

Also, Viagra may not be safe for people with certain medical conditions and those taking certain medications. This includes people with heart disease and people who take nitrates.

To make sure Viagra is safe for you to take, make sure your doctor knows about all your medical conditions and medications. Your doctor will discuss your risk of serious side effects and whether it’s safe for you to take.

How do the side effects of Viagra compare with those of its generic version?

The side effects of Viagra are the same as those of its generic version, sildenafil. The active ingredient in Viagra is sildenafil. Generic sildenafil is an exact copy of the active drug in Viagra. So, sildenafil is considered as safe and effective as Viagra because it’s an exact copy of the drug. This means it’ll have the same side effects as Viagra when taken at the same dosages.*

If you’d like more information about the generic version of Viagra, including its side effects, talk with your doctor or pharmacist.

* For information about the dosages of Viagra, see this article.

If I take Viagra, will my partner experience side effects?

No, if you take Viagra, your partner should not experience side effects from the drug.

Keep in mind that Viagra will not protect you or your partner from sexually transmitted infections (STIs). It also will not help prevent your partner from becoming pregnant. If you’re sexually active, be sure to use reliable birth control and practice safe sex to protect yourself and your partner.

If you have questions or concerns about taking Viagra, talk with your doctor or pharmacist.

Learn more about some of the side effects that Viagra may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Viagra.

Headache

Headache was the most common side effect reported in clinical trials of Viagra. It happens because Viagra widens your blood vessels. This helps you have an erection, but it can also cause headaches and other side effects.

In clinical trials, headache was dose-related. This means more people reported headaches with higher doses. (For information about the dosages of Viagra, see this article.)

What you can do

If you have headaches from Viagra, it’ll likely be temporary. For bothersome headaches, over-the-counter pain relievers may be helpful. Your doctor or pharmacist can suggest the right one for you.

If headaches become severe or long lasting, talk with your doctor. They can recommend ways to manage it.

Low blood pressure

Viagra can cause low blood pressure temporarily. This is because the drug works by relaxing blood vessels and increasing blood flow in the body, including the penis. This type of short-term low blood pressure was rarely reported in clinical trials of Viagra.

Symptoms can include:

  • dizziness
  • lightheadedness, which can lead to fainting
  • weakness

For most people, a temporary decrease in blood pressure isn’t a problem. However, it can be unsafe in people with heart disease or those who take certain medications, such as nitrates. Also, you may have an increased risk of developing low blood pressure from Viagra if you take other medications that can affect blood pressure. These include alpha-blockers and high blood pressure medications.

What you can do

If you feel dizzy or lightheaded after taking Viagra, you can lie down until you feel better. If this continues or happens again, contact your doctor.

Before taking Viagra, tell your doctor about all your medical conditions and medications. If you take medications for high blood pressure, talk with your doctor about whether Viagra is safe for you.

Non-arteritic anterior ischemic optic neuropathy

Non-arteritic anterior ischemic optic neuropathy (NAION) can occur while taking Viagra. NAION is a condition that can cause damage to the optic nerve, which is responsible for your vision. NAION was a rarely reported side effect after Viagra became available for use.

Symptoms can include:

  • a sudden decrease or loss of vision in one or both eyes
  • loss of contrast or light sensitivity
  • a dark shadow or blind area in the upper or lower half of your vision

In rare cases, NAION can cause permanent vision loss.

Note that NAION is different from the mild vision problems that were commonly reported in the clinical trials of Viagra. (For information about these mild vision problems, see the “Mild side effects of Viagra” section above.)

What you can do

If you have a sudden decrease or loss of vision in one or both eyes, seek immediate medical care. This includes going to the hospital or calling 911 or your local emergency number. Your doctor will have you stop taking Viagra if this side effect happens.

Priapism

Some people may experience priapism while taking Viagra. Priapism is a long lasting and painful erection that won’t go away. It was a rare, but serious side effect that occurred after Viagra became available for use.

In rare cases, priapism can cause permanent damage to your penis.

What you can do

Priapism requires medical care. If you have an erection that lasts more than 4 hours, go to the hospital or call 911 or your local emergency number. If you experience this side effect, your doctor will likely stop Viagra treatment.

Sudden hearing loss

Viagra may cause a sudden decrease or loss of hearing. This was rarely reported in clinical trials of the drug. Dizziness and tinnitus (ringing or buzzing in the ears) may occur along with hearing problems.

What you can do

Seek immediate medical care if you have a sudden decrease or loss of hearing while taking Viagra. This includes going to the hospital or calling 911 or your local emergency number. If you experience this side effect, your doctor will likely stop Viagra treatment.

Allergic reaction

As with most drugs, Viagra can cause an allergic reaction in some people. However, this side effect rarely occurred in clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Viagra. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Viagra. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

Allergic reaction. If you’ve had an allergic reaction to Viagra or any of its ingredients, your doctor will likely not prescribe Viagra. Ask your doctor about other medications that may be better options for you.

Bleeding problems. There have been reports of bleeding in people taking Viagra after it was approved for use. These problems weren’t reported in clinical trials of Viagra. It isn’t known if Viagra causes these problems or if it’s safe to use in people with bleeding problems. Tell your doctor about any bleeding problems you have or if you have an active stomach ulcer that can bleed. They’ll help determine whether Viagra is safe for you.

Blood cell problems. Certain blood cell problems may increase the risk of developing priapism.* This includes sickle cell disease, anemia, multiple myeloma, and leukemia. If you have a blood cell disease, ask your doctor if Viagra is right for you.

Use of guanylate cyclase stimulators. You should not take Viagra if you take a guanylate cyclase stimulator medication, such as riociguat (Adempas).† Taking these medications with Viagra can cause a sudden drop in blood pressure, which can lead to heart attack or stroke. Talk with your doctor about your other treatment options.

Heart and blood vessel disease. Your doctor usually won’t prescribe Viagra if you’ve had heart problems, stroke, or heart surgery in the last 6 months. Heart problems include angina (chest pain), irregular heartbeats, heart attack, heart failure, and aortic valve disease. If you have any of these conditions, ask your doctor if Viagra is safe for you and what other treatment options are available.

If you have chest pain, dizziness, or nausea during sex, stop sexual activity. Call 911 or your local emergency number if you think you’re having a heart attack or another life threatening emergency.

High blood pressure. People taking high blood pressure medications may have sudden drops in blood pressure when they take Viagra. If your high blood pressure is not managed well, it may not be safe for you to have sex. This is because high blood pressure can affect how well your heart works during sex. Talk with your doctor if you have high blood pressure or take medications to lower your blood pressure. They’ll help determine whether Viagra is safe for you. Or they’ll recommend other treatment options.

Liver or kidney problems. If you have liver problems or severe kidney problems, you may have an increased risk of side effects from Viagra. In these cases, doctors typically prescribe lower starting doses of Viagra.‡ Be sure to tell your doctor if you have liver or kidney problems. Your doctor will help determine the right dose of Viagra for you.

Use of nitrates. You should not take Viagra if you take nitrate medications. This includes prescription medications, such as nitroglycerin. It also includes illegal drugs, such as amyl nitrate. Taking these medications with Viagra can cause a sudden drop in blood pressure, which can lead to heart attack or stroke. Ask your doctor about your other treatment options for your condition.

Physical abnormalities of the penis. If you have physical problems with your penis, your doctor won’t likely prescribe Viagra. These problems include scarring or Peyronie’s disease. If you have these problems and have priapism* during Viagra treatment, you can damage your penis further. Tell your doctor about any physical problems with your penis. They’ll advise if Viagra is right for you.

Retinitis pigmentosa. Viagra hasn’t been studied in people with an eye condition called retinitis pigmentosa. So it isn’t known if it’s safe for people with this condition. Tell your doctor about any eye problems you have. Your doctor will advise if Viagra is right for you.

* For more details about this side effect, see the “Side effect specifics” section above.
† To learn about other drugs that interact with Viagra, view this article.
‡ For information about the dosages of Viagra, see this article.

Alcohol with Viagra

It’s unknown whether Viagra interacts with alcohol.

However, alcohol can cause many of the same side effects as Viagra. These include headache, flushing, and dizziness. Drinking alcohol with Viagra can worsen these side effects. In addition, consuming alcohol can worsen erectile dysfunction.

If you drink alcohol and you’d like to drink it while taking Viagra, talk with your doctor. They’ll help determine whether it’s safe for you to do so.

Pregnancy and breastfeeding while taking Viagra

It’s unknown whether it’s safe to take Viagra during pregnancy or while breastfeeding. The drug is not approved for use in people who can become pregnant.

Talk with your doctor if you have concerns about taking Viagra during pregnancy or breastfeeding.

If you’d like to learn more about Viagra, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.